Infectious diseases annually cause huge human and social damage in developing countries and elsewhere. In particular, malaria parasite infections annually infect 500 million people and cause the death of 2 million to 3 million people; however, no effective vaccine for the prevention of this disease has been developed. Therefore, there is an urgent need to develop a malaria vaccine.
However, in spite of many vaccine clinical tests conducted over the past 30 to 40 years, none of the developed vaccines showed efficacy and all efforts for vaccine development have been frustrated. In such circumstances, as a molecule recognized by an antibody having antimalarial activity, SERA (serine repeat antigen) protein was identified in the serum of adults who have acquired protective immunity (see, for example, Non-patent Literature (NPL) 1).
Later, the development of vaccines was conducted using recombinant SERA protein as an antigen. However, because the antibody titer of the obtained anti-SERA protein antibody is lower than that of Africans who have gained protection (immunity) against malaria parasite infections, further improvement has been desired.